Light-emitting device

ABSTRACT

A light-emitting device includes a heat-dissipating structure having a first part and a second part separated from the first part; a light-emitting unit including a light-emitting element with a first pad formed on the first part; and a first transparent enclosing the light-emitting element and having a sidewall; and an adhesive material covering a portion of the sidewall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending application Ser. No.15/867,315, filed on Jan. 10, 2018, which is a Continuation ofapplication Ser. No. 14/721,599 filed on May 26, 2015, for whichpriority is claimed under 35 U.S.C. § 120; and this application claimspriority of U.S. Provisional Application No. 62/003,262 filed on May 27,2014 under 35 U.S.C. § 119(e), the entire contents of all of which arehereby incorporated by reference.

REFERENCE TO RELATED APPLICATION

This application claims the right of priority based on U.S. provisionalapplication Ser. No. 62/003,262, filed on May 27, 2014. The entirecontent of the application is hereby incorporated by reference.

BACKGROUND Technical Field

The present disclosure relates to a light-emitting device, and moreparticularly to a light-emitting device disposed on a heat-dissipatingstructure.

Description of the Related Art

The light-emitting diodes (LEDs) of the solid-state lighting elementshave the characteristics of low power consumption, low heat generation,long operational life, shockproof, small volume, quick response and goodopto-electrical property like light emission with a stable wavelength sothe LEDs have been widely used in household appliances, indicator lightof instruments, and opto-electrical products, etc.

When a current is applied to an LED, the LED can emit light and usuallygenerates heat. If the heat is not efficiently dissipated, theperformance of LED may be adversely affected.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a light-emitting device. Thelight-emitting device includes a heat-dissipating structure having afirst part and a second part separated from the first part, alight-emitting unit including a light-emitting element with a first padformed on the first part, a first transparent enclosing thelight-emitting element and having a sidewall; and an adhesive materialcovering a portion of the sidewall.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings are included to provide easy understanding ofthe application, and are incorporated herein and constitutes a part ofthis specification. The drawings illustrate the embodiments of theapplication and, together with the description, serves to illustrate theprinciples of the application.

FIG. 1A is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 1B is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 1C is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 1D is a cross-sectional view of a light-emitting device inaccordance with a further embodiment of the present invention.

FIG. 2A is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 2B is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 2C is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 2D is a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention.

FIG. 3A is a perspective view of a light-emitting device in accordancewith an embodiment of the present invention.

FIG. 3B is a top view of a heat-dissipating structure shown in FIG. 3A.

FIG. 3C is a bottom view of a heat-dissipating structure shown in FIG.3A.

FIG. 3D is a cross sectional view taken along line AA′ in FIG. 3B.

FIG. 3E is a view taken along line BB′ in FIG. 3B.

FIGS. 4A-4F are cross-sectional views of the light-emitting units inaccordance to the aforesaid embodiments of present invention.

FIG. 4G is a cross-sectional view of the light-emitting unit of FIG. 4Adisposed on a heat-dissipating structure unit.

FIGS. 5A-5F, 6A-6H, 7A, and 7B are cross-sectional views of thelight-emitting units in accordance to the aforesaid embodiments ofpresent invention.

FIGS. 8A-8B show cross-sectional views of a light-emitting device inaccordance to other embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To better and concisely explain the disclosure, the same name or thesame reference number given or appeared in different paragraphs orfigures along the specification should has the same or equivalentmeanings while it is once defined anywhere of the disclosure.

The following shows the description of embodiments of the presentdisclosure in accordance with the drawings.

FIG. 1A show a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. Thelight-emitting device comprises a heat-dissipating structure 50 and alight-emitting unit 30 disposed on the heat-dissipating structure 50.The heat-dissipating structure 50 includes two parts 511 and two metallayers 512 formed on upper surfaces 5111 of the two parts 511,respectively. The two parts 511 are spaced apart from each other,thereby forming a space 503 therebetween. The metal layer 512 is made ofone or more metallic materials. The metallic material includes but notlimited to Al, Cu, Au, Ag, Sn, Ti, Ni, and an alloy thereof. The part511 is made of a conductive material or an insulating material. Theconductive material is made of one or more metallic materials asdescribed above. The insulating material is made of a thermosettingepoxy resin which has a triazine derived epoxy resin as its majorcomponent or a thermosetting silicone resin. The insulating material canoptionally include one or more reflective materials in the thermosettingepoxy resin. The reflective material includes but not limited to TiO₂,K₂TiO₃, ZrO₂, ZnS, ZnO, SiO₂, and MgO.

The light-emitting unit 30 is a flip-chip, and has a light-emitting body300 and two bonding pads 301, 302 mounted on the two metal layers 512 ofthe heat-dissipating structure 50, respectively, through a bump 27(solder bump or gold bump). In other embodiment, the light-emitting unit30 can be mounted on the heat-dissipating structure 50 through eutecticbonding or a conductive adhesive material (for example, throughAnisotropic Conductive Paste or Anisotropic conductive adhesivematerial).

An adhesive material 261 is provided between the light-emitting unit 30and the heat-dissipating structure 50 to enhance the mechanical strengththerebetween. The adhesive material 261 covers a portion of a sidewall3001 of the light-emitting body 300 without covering the entire sidewallof the light-emitting body 300. In addition, the adhesive material 261further covers entire side surfaces 3011, 3012 of the bonding pads 301,302 and entire side surfaces 271 of the bump 27. The adhesive material261 is made of an insulation material including but not limited tosilicone, epoxy, polyimide (PI), BCB, perfluorocyclobutane (PFCB), SU8,acrylic resin, polymethyl methacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), polyetherimide, andfluorocarbon polymer. In one embodiment, the adhesive material 261 caninclude a plurality of heat-conductive particles dispersed therein (notshown). The heat-conductive particles are made of one or more conductivematerials. The conductive material is such as gold, silver, aluminum,diamond, diamond-like carbon, grapheme, graphite, carbon nanotube, boronnitride, silicon carbide, beryllium oxide, and aluminum nitride. Theadhesive material 261 can be transparent or translucent.

FIG. 1B shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. As shown in FIG.1B, the adhesive material 261 can also be further provided between thebonding pad 301 and the bonding pad 302 to cover a bottom surface 3003of the light-emitting body 30 and the space 503 in the heat-dissipatingstructure 50. In this embodiment, the part 511 has a top surface 5111and a bottom surface 5112. The space 503 is fully filled with theadhesive material 261, that is, a lower surface 2611 of the adhesivematerial 261 can be coplanar with a bottom surface 5112 of the part 511.In other embodiment, the space 503 is partially filled with the adhesivematerial 261, that is, the lower surface 2611 is between the top surface5111 and the bottom surface 5112. In other embodiment, the metal layer512 can be further formed on the bottom surface 5112 opposite to the topsurface 5111.

FIG. 1C shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. As shown in FIG.1C, a reflective layer 265 is formed between the adhesive material 261and the heat-dissipating structure 50 for reflecting the light emittedby the light-emitting unit 30 upwardly. The reflective layer 265 can bea single layer or a multi-layer. If the reflective layer 265 is a singlelayer, the reflective layer 265 can be made of a conductive material oran insulating material. The conductive material includes but not limitedto Ag, Al, and Au. The insulating material is such as a white paintwhich includes a plurality of diffusion particles dispersed insilicone-based or epoxy-based matrix. The diffusion particle is made ofone or more materials. The material is such as TiO₂, ZnO, and ZrO₂. Ifthe reflective layer 265 is a multi-layer, the reflective layer 265 caninclude a plurality of metal oxide layers (made of one or morematerials, such as SiO₂, Al₂O₃ and Si₃N₄) or semiconductor layers (madeof one or more materials, such as GaN, AlGaN, AlInGaN, AlAS, AlGaAs andGaAs) with an alternately-arranged layer structure, such as aDistributed Bragg Reflector structure. Alternatively, the reflectivelayer 265 can include a plurality of metal layers. The metal layer canbe made of one or more reflective metals, such as Ag, Al, Au, Ti, Cr,Ni, and an alloy thereof.

FIG. 1D shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. As shown in FIG.1D, Each of the two parts 511 has an extension 5113 sticking out from aportion near the metal layer 512. The extensions 5113 of the two parts511 face each other in a horizontal direction and space apart by adistance which is smaller than a gap of the two parts 511 beneath theextensions. The distance can be made to spatially correspond to a gap ofthe bumps 27. However, the distance between the extensions 5113 and thegap of the bumps 27 are not necessarily made equal. The adhesivematerial 261 can be formed in a space between the parts 511 but not in aspace 5121 between the metal layers 512 such that an air gap is formedbetween the light-emitting body 30 and the adhesive material 261. Inaddition, the adhesive material 261 can further cover a sidewall 5114 ofthe part 511 opposite to the protrusion 5113.

FIG. 2A shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. As shown in FIG.2A, the adhesive material 261 is optionally formed to enclose the entiresidewalls 3001 and a top surface 3002 of the light-emitting body 300such that the adhesive material 261 can be used as a lens. A pluralityof heat-conductive particles can be also dispersed in the adhesivematerial 261.

FIG. 2B shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. As shown in FIG.2B, the adhesive material 261 can be optionally formed between thebonding pad 301 and the bonding pad 302 to cover the bottom surface 3003of the light-emitting body 30 and filled in the space 503 in theheat-dissipating structure 50. The related descriptions can refer toother paragraphs.

FIG. 2C shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present invention. FIG. 2D show across-sectional view of a light-emitting device in accordance with anembodiment of the present invention. FIGS. 2C and 2D illustratestructures similar to those shown in FIGS. 2A and 2B. The adhesivematerial 261 is formed to possess a recess 2612 at a position rightabove the light-emitting body 300. In FIG. 2D, the adhesive material 261is further formed between the bonding pads 301, 302. The adhesivematerial 261 can be formed in various shapes, depending on actualrequirements for achieving a desired light distribution or color overangle (COA).

FIG. 3A shows a perspective view of a light-emitting device inaccordance with an embodiment of the present invention. Thelight-emitting device has a heat-dissipating structure 60 and alight-emitting unit 30 (shown in dotted line) disposed on theheat-dissipating structure 60. FIG. 3B illustrates a top view of theheat-dissipating structure 60. FIG. 3C illustrates a bottom view of theheat-dissipating structure 60. FIGS. 3D and 3E illustratecross-sectional views of the heat-dissipating structure 60. FIG. 3D is aview taken along line AA′ of FIG. 3B. FIG. 3E is a view taken along lineBB′ of FIG. 3B.

As shown in FIGS. 3A, 3B and 3D, the heat-dissipating structure 60includes two spaced-apart metal parts 521 and an insulating structure522 provided to clamp the metal parts 521 together. Specifically, theinsulating structure 522 has a first portion 5221 between the metalparts 521, and a second portion 5222 extending from a front side of themetal part 521 to a back side of the metal part 521 and penetratingthrough the entire metal part 521. One of the metal parts 521 has anextension 5211 extending toward the other of the metal parts 521.

As shown in FIGS. 3A, 3B and 3E, the insulating structure 522 has athird portion 5223 formed to cover a sidewall of the metal part 521. Inthis embodiment, the first portion 5221, the second portion 5222, andthe third portion 5223 are integratedly formed to make the insulatingstructure 522 a single object.

The metal part 521 is made of one or more metallic materials. Themetallic material includes but not limited to Al, Cu, Au, Ag, Sn, Ti,Ni, and an alloy thereof. The insulating structure 522 is made of athermosetting epoxy resin which has a triazine derived epoxy resin asits major component or a thermosetting silicone resin. The insulationstructure 522 can optionally include one or more reflective materials inthe thermosetting epoxy resin. The reflective material includes but notlimited to TiO₂, K₂TiO₃, ZrO₂, ZnS, ZnO, and MgO.

FIGS. 4A-4F, 5A-7B show cross-sectional views of the light-emittingunits 30 shown in FIGS. 1A-3A in accordance to the aforesaid embodimentsof present invention. FIG. 4G shows a cross-sectional view of thelight-emitting unit of FIG. 4A disposed on the heat-dissipatingstructure 50.

As shown in FIG. 4A, the light-emitting unit 30 includes alight-emitting element 40 with a first electrode 401 and a secondelectrode 402, a first transparent structure 52 enclosing thelight-emitting element 40, a second transparent structure 51 formed onthe first transparent structure 52. A reflective layer 53 is formed onthe first transparent structure 52 at a side opposite to the secondtransparent structure 51, and has a first portion 531, a second portion532, and a third portion 533 between the first electrode 401 and thesecond electrode 402. The first portion 531 is adjacent to the firstelectrode 401 and has a height gradually increasing in a direction fromthe first electrode 401 to an edge of the first transparent structure52. The second portion 532 is adjacent the second electrode 402 and hasa shape similar to that of the first portion 531, therefore, the secondportion 532 has a height gradually increasing in the direction from thesecond electrode 402 to another edge of the first transparent structure52. The third portion 533 has a convex shape with a central regionbulged outwards in a direction far away from the light-emitting element40. In this embodiment, a first pad 541 is formed on the first portion531 and the first electrode 401 and electrically connected to the firstelectrode 401. Specifically, the first pad 541 has a footprint arealarger than that of the first electrode 401, thereby increasing acontacting area with the bump 27 (as shown in FIG. 1A). A second pad 542is formed on the second portion 532 and the second electrode 402 andelectrically connected to the second electrode 402. Likewise, the secondpad 542 has a footprint area larger than that of the second electrode302, thereby increasing a contacting area with the bump 27 (as shown inFIG. 1A). The first pad 541 has a shape similar to that of the secondpad 542 and has a sidewall 5411 adjacent to the second pad 542. Thesidewall 5411 has a concave surface.

Specifically, the light-emitting body 300 in FIG. 1A includes thelight-emitting element 40 with the first electrode 401 and the secondelectrode 402, the first transparent structure 52, the secondtransparent structure 51, and the reflective layer 53 as shown in FIG.4A. The first pad 541 and the second pad 542 are used as the bonding pad301 and the bonding pad 302, respectively (as shown in FIGS.1A-3B), formounting on the heat-dissipating structure 50.

Referring to FIG. 4G, the adhesive material 261 cover a portion of asidewall of the first transparent structure 52 without covering asidewall of the second transparent structure 51. In addition, since agap 43 can exist between the first portion 531 of the reflective layer53 and the first pad 541, the adhesive material 261 can be filled intothe gap. Alternatively, the adhesive material 261 can cover the entiresidewall of the first transparent structure 52 and only a portion of thesidewall of the second transparent structure 51 for enhancing amechanical strength between the light-emitting unit 30 and theheat-dissipating structure 50.

As shown in FIG. 4B, the light-emitting unit 30 has a structure similarto that shown in FIG. 4A, except that a phosphor layer 55 is providedwithin the first transparent structure 52. The phosphor layer 55includes a plurality of phosphor particles dispersed therein to absorband convert a first light emitted by the light-emitting element 40 to asecond light with a peak wavelength different from that the first light.The phosphor particle includes, but is not limited to, yellow-greenishphosphor and red phosphor. The yellow-greenish phosphor includesaluminum oxide (such as YAG or TAG), silicate, vanadate, alkaline-earthmetal selenide, or metal nitride. The red phosphor includes silicate,vanadate, alkaline-earth metal sulfide, metal nitride oxide, a mixtureof tungstate and molybdate. The first light can be mixed with the secondlight to produce a white light. The lighting apparatus 100 has a colortemperature of 2200K-6500K (ex. 2200K, 2400K, 2700K, 3000K, 5700K,6500K) and a color point (CIE x, y) is within a seven-step MacAdamellipse.

As shown in FIG. 4C, the light-emitting unit 30 has a structure similarto that shown in FIG. 4A, except that the second transparent structure51 has a chamfer 518.

As shown in FIG. 4D, the light-emitting unit 30 has a structure similarto that shown in FIG. 4C, except that a phosphor layer 55 is providedwithin the first transparent structure 52. The description of thephosphor layer 55 can refer to other embodiments.

As shown in FIG. 4E, the light-emitting unit 30 has a structure similarto that shown in FIG. 4A, except that the first transparent structure 52extends beyond the second transparent structure 51 and has an arc 521close to the second transparent structure 51.

As shown in FIG. 4F, the light-emitting unit 30 has a structure similarto that shown in FIG. 4E, except that a phosphor layer 55 is providedwithin the first transparent structure 52.

FIGS. 5A-5F have structures similar to those shown in FIGS. 4A-4F,except that the light-emitting units are devoid of the reflective layerand the pads. The first electrode 401 and the second electrode 402 areused as the bonding pads 301, 302, respectively, for mounting on theheat-dissipating structure 50.

FIGS. 6A and 6B have structures similar to those shown in FIGS. 4E and4F, except that a reflective structure 56 is formed between the firsttransparent structure 52 and the second transparent structure 51. Thereflective structure 56 can be a single layer or a multi-layer. If thereflective structure 56 is a single layer, the reflective structure 56can be made of a conductive material or an insulating material. Theconductive material includes but not limited to Ag, Al, and Au. Theinsulating material is such as a white paint which includes a pluralityof diffusion particles dispersed in silicone-based or epoxy-basedmatrix. The diffusion particle is made of one or more materials. Thematerial is such as TiO₂, ZnO, and ZrO₂. If the reflective structure 56is a multi-layer, the reflective structure 56 can include a plurality ofmetal oxide layers (made of one or more materials, such as SiO₂, Al₂O₃and Si₃N₄) or semiconductor layers (made of one or more materials, suchas GaN, AlGaN, AlInGaN, AlAS, AlGaAs and GaAs) with analternately-arranged layer structure, such as a Distributed BraggReflector structure. Alternatively, the reflective structure 56 caninclude a plurality of metal layers. The metal layer can be made of oneor more reflective metals, such as Ag, Al, Au, Ti, Cr, Ni, and an alloythereof.

FIGS. 6C and 6D have structures similar to those shown in FIGS. 4A and4B, except that the light-emitting units are devoid of the secondtransparent structure 51 formed on the first transparent structure 52.

FIGS. 6E and 6F have structures similar to those shown in FIGS. 6C and6D, except that the light-emitting units are devoid of the reflectivelayer and the pads.

FIG. 6G has a structure similar to that in FIG. 6F, except that thephosphor layer 55 is conformably formed on the light-emitting element40, that is, the phosphor layer 55 is formed along the contour of thelight-emitting element 40.

FIG. 6H has a structure similar to that in FIG. 6E, except that thefirst transparent structure 52 is not provided.

As shown in FIG. 7A, a phosphor structure 57 encloses the light-emittingelement 40. The phosphor structure 57 includes a plurality of phosphorparticles dispersed in a matrix body. Alternatively, the phosphorstructure 1413 can further include diffusing particles. The matrix bodyincludes epoxy, silicone, PI, BCB, PFCB, Su8, acrylic resin, PMMA, PET,PC, or polyetherimide. The diffusing particle includes titanium oxide,zirconium dioxide, zinc oxide, or aluminum oxide. The description of thephosphor particle can refer to other embodiments.

FIG. 7B has a structure similar to that shown in FIG. 7A, except thatthe reflective layer 53 and the pads 541, 542 are further provided.

FIGS. 8A-8B illustrate cross-sectional views of a light-emitting devicein accordance to another embodiments. The light-emitting devicecomprises a carrier 61, two spaced-apart metal layers 512 formed on atop surface 611 of the carrier 61, and the light-emitting unit 30. Thelight-emitting unit 30 has a first bonding pad 301 and a second bondingpad 302, respectively, mounted on the two spaced-apart metal layers 512through a bump 27 such as solder bump or gold bump. In other embodiment,the light-emitting unit 30 can be mounted on the two spaced-apart metallayers 512 through eutectic bonding or a conductive adhesive material(for example, through anisotropic conductive paste or anisotropicconductive adhesive material).

A reflective layer 515 is optionally formed on the metal layers 512 orthe carrier 61 for reflecting the light emitted by the light-emittingunit 30. The reflective layer 515 includes a single layer or amulti-layer. If the reflective layer 515 is a single layer, the singlelayer can be made of a conductive material, or an insulating material.The conductive material includes but not limited to Ag, Al, and Au. Theinsulating material is such a white paint which includes a plurality ofdiffusion particles dispersed in a silicone-based or epoxy-based matrix.The diffusion particle is made of one or more materials. The material issuch as TiO₂, ZnO, and ZrO₂. If the reflective layer 515 is amulti-layer, the reflective layer 515 can include a plurality of metaloxide layers (made of one or more materials, such as SiO₂, Al₂O₃ andSi₃N₄) or semiconductor layers (made of one or more materials, such asGaN, AlGaN, AlInGaN, AlAS, AlGaAs and GaAs) with an alternately-arrangedlayer structure, such as a Distributed Bragg Reflector structure.Alternatively, the reflective layer 515 can include a plurality of metallayers. The metal layer can be made of one or more reflective metals,such as Ag, Al, Au, Ti, Cr, Ni, and an alloy thereof.

In top view, the metal layer 512 has a surface area at least two timesgreater than an area of the corresponding first bonding pad 301 or thesecond bonding pad 302. The carrier 61 is made of a thermosetting epoxyresin which has a triazine derived epoxy resin as its major component ora thermosetting silicone resin. The carrier 60 can optionally includeone or more reflective materials disposed therein. The reflectivematerial includes but not limited to TiO₂, K₂TiO₃, ZrO₂, ZnS, ZnO, andMgO.

As shown in FIG. 8B, two additional spaced-apart metal layers 512 can beoptionally formed on a bottom surface 612 at a position corresponding tothe spaced-apart metal layers 512 on the top surface 611. A plurality ofconductive via holes 520 are formed within and to penetrate the carrier60 for electrically connecting the metal layer 512 on the top surface611 with the metal layers 512 on the bottom surface 612.

As shown in FIG. 8A, heat generated from the light-emitting unit 30 isdissipated by the metal layer 512 to the environment. On the contrary,ss shown in FIG. 10B, by the via holes 520 connecting the metal layer512 on the top surface 611 with the metal layer 512 on the bottomsurface 612, heat can be dissipated not only by the metal layer 512 onthe top surface 611 but also by the metal layer 512 on the bottomsurface 612. Accordingly, the total heat-dissipating area is enlarged,compared to the conditions shown in FIG. 10A, for facilitating heatdissipation from the light-emitting unit 30 to the environment.

The foregoing description has been directed to the specific embodimentsof this invention. It will be apparent to those having ordinary skill inthe art that other alternatives and modifications can be made to thedevices in accordance with the present disclosure without departing fromthe scope or spirit of the disclosure. In view of the foregoing, it isintended that the present disclosure covers modifications and variationsof this disclosure provided they fall within the scope of the followingclaims and their equivalents.

What is claimed is:
 1. A light-emitting device comprising: aheat-dissipating structure including a first part and a second part, thefirst part being separated from the second part; a first metal layer anda second metal layer, the second metal layer being separated from thefirst metal layer, the first metal layer being placed on the first part,the second metal layer being placed on the second part; a light-emittingunit having outer sidewalls and a top surface, the light-emitting unitincluding: a light-emitting element having a first electrode and asecond electrode, the first electrode being separated from the secondelectrode; a transparent structure enclosing the light-emitting element;a first pad electrically connected to the first electrode; a second padelectrically connected to the second electrode; and a reflectivestructure formed on the transparent structure, wherein the first partand second part, the first metal layer and second metal layer, and thelight-emitting unit collaboratively define a space; and an adhesivestructure placed between the light-emitting unit and theheat-dissipating structure, a first part of the adhesive structure beingfilled in the space, and a second part of the adhesive structurecovering the outer sidewalls and the top surface of the light-emittingunit to form a dome shape.
 2. The light-emitting device of claim 1,wherein the reflective structure is a single layer.
 3. Thelight-emitting device of claim 1, wherein the reflective structureincludes a plurality of metal layers.
 4. The light-emitting device ofclaim 1, wherein the adhesive structure is made of an insulationmaterial.
 5. The light-emitting device of claim 1, wherein thelight-emitting unit is a flip-chip.
 6. A light-emitting devicecomprising: a heat-dissipating structure including a first part and asecond part separated from the first part; a first metal layer and asecond metal layer separated from the first metal layer, the first metallayer being placed on the first part and the second metal layer beingplaced on the second part; a light-emitting unit having outer sidewallsand a top surface, including a first pad and a second pad, the first padbeing separated from the second pad, wherein the first part and secondpart, the first metal layer and second metal layer, and thelight-emitting unit collaboratively define a space; and an adhesivestructure placed between the light-emitting unit and theheat-dissipating structure, a first part of the adhesive structure beingfilled in the space and a second part of the adhesive structure coveringthe outer sidewalls and the top surface of the light-emitting unit toform a recess at a position right above and vertically aligned with thelight-emitting unit.
 7. The light-emitting device of claim 6, whereinthe adhesive structure includes a plurality of heat-conductiveparticles.
 8. The light-emitting device of claim 6, wherein the adhesivestructure is transparent or translucent.
 9. The light-emitting device ofclaim 6, wherein the adhesive structure is made of an insulationmaterial.
 10. The light-emitting device of claim 6, wherein thelight-emitting unit is a flip-chip.